题干
There is a blackboard __________ the classroom.
A：at front of
B：at the front of
C：in front of
D：at front
答案(点此获取答案解析）
B
There is a blackboard __________ the classroom.
A：at front of
B：at the front of
C：in front of
D：at front
，已知断裂1molN－N吸收167kJ热量，生成1mol N≡N放出942kJ热量。根据以上信息和数据，则由N2气体生成1mol气态N4的△H为（ ）
